Study associated with the datasets and code: "Female embryos are more likely to die than males in a wild mammal"

Author names, contact details : Mathieu Douhard (mathieu.douhard@univ-lyon1.fr); Eric Baubet (eric.baubet@ofb.gouv.fr); Marlène Gamelon (marlene.gamelon@univ-lyon1.fr).

Summary of the study : Biased birth sex ratios have been documented in many mammalian populations, but it is often difficult 
to know whether they result from biases in the sex ratio at conception and/or sex differences in prenatal mortality. It is generally
admitted that there is an excess of males at conception and a higher level of mortality during gestation for males due to a 
positive relationship between size and vulnerability. Here, we challenge this classical prediction in a wild boar (Sus scrofa) 
population facing highly variable food resources (mast seeding) and in which male fetuses are heavier than females. Using long-term
hunting and mast seeding data, we show that sex ratio at conception is balanced, and that females suffer from higher embryonic 
mortality particularly in large litters, whatever the level and the type of food resources. One possible explanation is that 
a female embryo is ready for implantation later than an identically-aged male due to slower development, and is more likely 
to miss the implantation window. To what extent a lower survival of female embryos is a common feature in mammals remains 
to be carefully explored. 

Responsibles for collecting data: Eric Baubet
Responsibles for writing code: Mathieu Douhard and Marlène Gamelon

List of all files by name:

- code_R, this file allows reproducing all tables and figures shown in the manuscript

- data_wildboar, this data file contains the following 7 variables
# year: the definition of “year” is based on hunting seasons and the seasonality of mast production, thus starting in October 1st and ending in September 30th the next civil year. 
# Mast: four categories depending on the quantity of beechnuts and acorns found in the stomachs during the hunting period 
# Weight_Mother: Maternal body mass (kg)
# LS:the number of fetus counted within pregnant females when shot during the hunting season
# nb_males: number of male fetuses in the litter
# nb_females: number of female fetuses in the litter
# ME:Embryonic mortality

Software used: R version 4.1.2   




